I am reading up on Vandermonde's Identity, and so far I have found proofs for the identity using combinatorics, sets, and other methods. However, I am trying to find a proof that utilizes mathematical induction. Does anyone know of such a proof?

The induction could be donde over r?. Also, suppose we talk about the general version of this identity, with m and n possibly complex values, and r integer. We can do an induction proof over r?.
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Wyvern666Jan 24 '14 at 17:26